Wet masterbatch might, for example, be manufactured using a procedure in which carbon black is added to water or other such liquid and this is agitated to prepare a carbon black slurry, the carbon black slurry and natural rubber latex are mixed, this is coagulated, the coagulum is dewatered, and plasticization is carried out as this is being dried.
Wet masterbatch manufactured in accordance with such a procedure has superior ability to achieve reduced heat generation in vulcanized rubber as compared with dry masterbatch. A dry masterbatch is a masterbatch produced by causing carbon black to be dry-kneaded into rubber.